In 6 growth hormone-sufficient patients of a pilot study, we have shown synchronicity between nocturnal fluctuations of growth hormone (gh) and picp, a serum marker of biosynthesis of type I procollagen. We also discoverd down-regulation of picp conicident with the am rise in cortisol (f). We now intend to further clarifyy the modulation of picp by 1. The physiological fluctuation of endogenous gh and f; 2 the administration of exogenous gh; and by 3. The inhibition of endogenous f. We will include profibrotic hormone aldosterone, which also shows diurnal variablility in both gh-deficient and gh sufficient patients.